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March 17, 1964 H. R. DALToN 3,125,021

ELECTRO-RESPONSIVE FACSIMILE RECORDING AND PLANOGRAPHIC PLATE Filed Nov. 14, 1955 Full- 1Q (mK- xzcsprv: Recogo) HAROLD R. DALroN INVENTOR.

BY i

TORNEY 3,125,021 ELECTRO-RESPONSIVE FACSIMILE RECORDING AND PLANOGRAPHIC PLATE Harold R. Dalton, Jenkintown, Pa., assignor to Timefax Corporation, New York, N.Y., a corporation of New York Filed Nov. 14, 1955, Ser. No. 546,400 7 Claims. (Cl. lOl-149.2)

vnovel electro-responsive paper plate which is prepared and treated so as to render it responsive to applied electric voltages so as to render such areas alone ink receptive when used in conventional offset or lithographie printing processes.

Another object is to provide a novel electro-sensitive recording paper of the electrochemical facsimile signal recording kind, which paper can also be used as a planographic or lithographie master to duplicate the recorded facsimile signals.

A feature of the invention relatesto a recording paper of the electrochemical kind which, in response to stylusapplied electric currents at selected elemental areas, develops a modified ionic condition at such areas so that a deposit is produced at such areas to render them receptive to ink by the offset printing process, whereas the remaining areas are not receptive to such ink.

Another feature relates to an improved planographic plate constituted of a novel paper sheet material.

Another feature relates to a planographic plate constituted of a paper impregnated with chemical salts and other substances capable of producing electrical conductivity in the paper when moist, and which will be responsive to stylus-applied voltage to produce a mark which is ink receptive whereas the areas of the paper not subjected to the stylus-applied voltage will not be ink receptive.

A further feature relates to the novel combination of elements which cooperate to constitute an improved facsimile recording blank which can also be used as a planograph masterl for duplicating the recorded subject matter. p

Other features and advantages, not specifically enumerated, will be apparent after a consideration of the following detailed descriptions and the appended claims.

In the drawing, i i

FIG. l is a magnified cross sectional view of part of an electrolytic paper according to the present invention; FIG. 2 is a cross sectional view of the paper of FIG. 1 after it has been subjected to the facsimile recording signals;

FIG. 3 is a modification of the blank of FIG. l.

The art of electrolytic recording papers has reached a comparatively high state'of development. However, the art heretofor has been concerned mainly, if not entirely, with the manufacture of so-called electrolytic papers which can be subjected to electrical voltages at selected areas so as to produce a permanent and well defined color change in the paper to represent the subject matter being recorded. Typical of such developments are those disclosed in U.S. Patents No. 2,683,111, No. 2,038,486, No. 2,063,992, and in co-pending application Serial No. 542,752 filed October 25, 1955, now abandoned. However, so far as I am aware, none of the prior electrolytic recording' papers is capable, after having the subject matter recorded thereon, of being used as a master in conventional offset or lithographie printing machines with satisfactory results. Probably one of United States Patent 3,125,021 Patented Mar. 17, 1964 lCe the reasons for that limitation of the prior electrolytic papers is that the paper stock usedfor carrying the electrolytic salts is not suiciently selective to the reception of ink in the recorded areas, and not sufficiently selective to the rejection of ink in the non-recorded areas. I have found that by making the electrolytic paper of hardwood sulfite pulp, it is possible to produce paper plates which perform satisfactorily the double function of electrolytic facsimile recording papers and as planographic or offset printing masters.

As is well known in the electrolytic facsimile recording art. the marking record is made by interposing the electrolytic paper while in a suitably moist condition, between a pair of electrically energized electrodes which define an elemental recording area. The flow of current through the paper in accordance with the variations in signal voltage brings about the liberation or concentration of ions at one or both of the electrodes, which results in the development of a color contrast or mark on the paper sheet. As is well known, this marking action can be effected in a variety of ways, for example (l) by the introduction of foreign ions in the paper stock, (2) by the discharge of ions at one of the electrodes in contact with the paper, (3) by oxidation or reduction at the electrode surface in contact with the paper, and (4) by increasing the concentration of a particular ion at the surface of an electrode in Contact with the paper so as to effect a pH change. However, preferably the mark is produced in carrying out the present invention by a charring or pitting of the surface of the paper, or by removal and deposition of metal from one of the electrodes in contact with the paper, which metal may react with compounds contained within the paper, or even by the formation of a colored organic complex in the surface of the paper. In accordance with the invention, the only requisites arethat the mark produced on the paper be permanent and selectively receptive to ink, for example as applied in an offset printing press. It is difficult to say just what are the reasons for the surface of the paper affected bythe recording current becoming ink receptive. There are probably a number of effects taking place either individually or collectively. The surface of the paper may be charred or pittedwhich is known to be conducive to ink receptivity. The deposit of metal on the surface of the paper, in colloidal form will also form an area which will be ink receptive. The

^ reaction of this metal with salts in the paper may also form a surface condition that will attract ink. For a detailed description of the various electrochemical marking actions and typical known compositions and ingredients, reference may be had to the Proceedings of the Institute of Radio Engineers, October 1948, pages 1224- 1235.

In accordance with the present invention, the electrolytic recording plate or paper is made from pulp of hardwood, and using the well known suliite process. I have found that sufficient hardwood pulp should be used so that in the finished paper'it constitutes at least 50 percent of the weight. As is well known, the hardwoods are the woods from deciduous trees, like mahogany, beech, birch, maple. Furthermore, if the paper is made of soft wood pulps, I have found that it does not have the basic characteristics for planographic or offset printing work, namely the ability to reject ink effectively. As is well known, soft woods are from the coniferous trees, such as spruce, pine, fir, balsam, hemlock. Heretofore, wherever electrolytic recording papers have been made, they have been made from papers which have a marked tendency to pick up ink over their entire surface, or they wrinkle so badly that they become useless for the production of copies of the recorded matter in an offset press.

At the time the hardwood sulfite pulp is being beaten in the beater associated with any well known paper making machine, there is added a material which irnparts pronounced wet strength to the finished paper. Examples of such materials are the following: Ureaformaldehyde resins, melamine-formaldehyde resins, polyvinyl resin lattices, etc.v It will be understood that this wet strength material may be added either at the pulp beating stage or at some subsequent stage by passing the partly finished paper sheet through a suitable bath or tub which may be a part of the paper making machine. If desired, the wet strength material may be added both in the beater stage and in a subsequent bath. For a disclosure of the pulping process in general use and the wet strength treatment of paper, reference is made to The Manufacture of Pulp and Paper, prepared by representatives of the pulp and paper industries of the United States and Canada, published by McGraw-Hill Book Co., Inc.

In accordance with the invention, a hydrophilic binder or resin, such as casein, viscose, algin, polyvinyl alcohol, polyvinyl methyl ether maleic anhydride copolymer, methyl cellulose, carboxy methyl cellulose, etc., may be added from a bath on the paper machine before the paper has become thoroughly dry, which will give to the surface of the sheet a more desirable fiinsh. These hinder materials may be added to constitute from percent to 2O percent of the dry weight of the sheet. Suitable pigment, such for example as colloidal silica, clay. titanium dioxide, etc., may be added together with the hydrophilic binder, the pigment constituting from 25 percent to 50 percent of the weight of the binder. It will be understood that the binder can be incorporated in the sheet by any of the procedures well known in the paper making art.

As is clear from the foregoing, any well known method of making paper from sulfite pulp can be used, the only modification being that at a suitable stage in the paper making operation the wet strength ingredient is added. The pulp batch is subjected to the well known drying procedures using either a Fourdrinier type machine or any other well known drying equipment used in paper making machines. As is well known, the drying occurs in stages. However, before the batch is thoroughly dry, and as staged hereinabove, it is passed through a bath containing any of the hydrophilic binders above mentioned. Thereafter the pulped batch is subjected to the remaining drying stages, and, if necessary, to any well known calendering stage. For a detailed description of a typical paper making machine that may be used to make the paper according to the invention, reference may also be had to the book entitled The Manufacture of Pulp and Paper, published by McGraw- Hill Book Company, 2nd edition 1929, volume V, section 1, part 5.

After the resin treatment, the paper is processed to render the binder or resin water resistant by any well known process. For example, in the case of casein, water resistance can be obtained by treating the paper surface with a water solution of formaldehyde, or with a solution of a heavy metal salt, such for example as ferrie chloride. On the other hand, if the binder is of viscose, the water resistance should be obtained by a further treatment with a solution of sodium chloride, alcohol, and the like, so as to convert the viscose into regenerated cellulose. After the paper has been formed, treated, and dried, one surface thereof, for example the upper surface, as seen in FIG. l, is given a smooth finish for example by calendering or by passing the sheet around a polished drum. It will be understood that the invention is not limited to any particular materials for making the binder water resistant.

As a result of the foregoing described method of manufacture the finished sheet is a paper base material consisting of at least 50 percent hardwood sulfite pulp having pronounced wet strength properties and having one smooth surface containing a light weight coating or film of a water resistant hydrophilic material either with or without a pigment. In fact, such papers can be used as planograph or offset printing blanks. In accordance with the invention, the blank so prepared is impregnated with any well known chemical compound or compounds such for example as sodium chloride, nitrates or sulphates, to make the blank sensitive to electric signal voltages when the paper is moistened and interposed between the recording electrodes. Any one of the four methods of effecting the recording marking, as hereinabove mentioned, may be employed.

FIG. l of the drawing shows in magnified cross section part of an electrolytic recording and offset printing blank 10 according to the invention. It will be observed that the upper surface of the blank is smooth, dense and water resistant, but nevertheless is hydrophilic, while the lower surface 12 may be of ordinary smoothness and density. When a recording voltage is applied across the electrodes 13 and 14 from any well known source of electric signals 15, the electrolytic action takes place at the elemental region of the blank between the opposed electrodes. This produces a characteristic permanent surface mark 16, as indicated in FIG. 2. At the same time the characteristics of the smooth upper surface 11 at these recorded elemental areas are changed, so that each such area, instead of being non-receptive to ink, now becomes receptive to the inks such as those conventionally used in offset or planographic printing machines. The remainder of the upper surface 1l, where no electrolytic recording has taken place, remains hydrophilic so that it takes up the water from the usual water blanket of the offset printing machine, and maintains the unrecorded areas non-receptive to ink.

In the event that the paper which forms the blank 10 contains a viscose binder which has been converted to regenerated cellulose, as above described, the upper surface 11 of the blank consists of such regenerated cellulose which is normally hydrophilic but not ink receptive except at those areas which have been acted upon by the signal currents. While FIG. 1 shows the blank with only one surface smoothed, it will be understood that where the smoothing is effected by certain types of calendering or smoothing machines, both the opposite surfaces of the blank can be smoothed as indicated in the embodiment of FIG. 3. It will be understood that the showing of the thickness of the paper blanks in FIGS. l, 2, and 3 and the smooth hydrophilic coating is essentially schematic. In any event the thickness of the hydrophilic coating is so small as not to appreciably interfere with the flow of electrolytic recording current through the blank. Furthermore, while the hydrophilic surface 11 is shown as a discrete layer in FIGS. 1, 2, and 3, it will be understood that the line of demarcation between the hydrophilic surface and the remainder of the paper blank is not necessarily a sharp one. Merely for convenience in the description and the claims, it is referred to as a coating, but actually it may form a relatively minutely thin stratum of the paper. By the expression hardwood as used herein is meant wood derived from the deciduous trees, such as mahogany, beech, birch and maple.

What is claimed is:

1. An electro-responsive planographic plate especially prepared to produce a facsimile record by electrolytic action in response to applied voltage at selected areas of the plate, said plate consisting of a paper having at least 50 percent hardwood sulfite pulp mixed with a wet strength imparting ingredient, said paper having incorporated therein during manufacture a water resistant but hydrophilic material to provide the paper with a smooth hydrophilic water resistant surface, the paper also containing an impregnation of a chemical electrolytic marking compound to render it electrically responsive to applied voltages to produce corresponding record marked areas which are ink receptive.

2. A planographic plate according to claim 1 in which said smooth surface is in the form of a light weight coating of regenerated cellulose.

3. A planographic plate according to claim 2 in which said light weight coating also includes colloidal silica pigment.

4. The method of making a'composite facsimile signal recording blank and planographic printing master which comprises forming a paper base with a mixture consisting of at least 50 percent hardwood sulte pulp containing a wet strength imparting ingredient and a hydrophilic binder. imparting a smooth finish to at least one surface of the paper, subjecting the paper surface to a water resisting treatment to make said surface water resistant but hydrophilic, impregnating the paper base with an electrolytic salt, and then subjecting said surface to a facsimile recording voltage to convert corresponding areas of said surface into ink receptive areas.

5. An electro-sensitive planographic printing plate, in the form of a paper, the body of which consists of at least fifty percent hardwood sultite pulp which includes a wet strength ingredient. as well as a hydrophilic binder to form the body of the paper with a hydrophilic stratum at the surface thereof, said paper also including in the body thereof an impregnant of a chemical cornpound which forms an electrolyte when damp to render the plate sensitive to applied electric voltages when damp and to produce at localized areas on the surface of the plate recording marks which are ink receptive while leaving the non-recorded areas of the plate hydrophilic.

6. An electro-sensitive planographic printing plate according to claim 5 in which said binder and said stralum in the body of the paper are regenerated cellulose.

References Cited in the le of this patent UNITED STATES PATENTS 2,056,294 Richter Oct. 6, 1936 2,132,443 Simons Oct. 11, 1938 2,156,100 Simons Apr. 25, 1939 2,229,091 Kline Jan. 21, 1941 2,316,340 Kohn Apr. 13, 1943 2,342,713 Wescott Feb. 29, 1944 2,419,296 Solomon Apr. 22, 1947 2,497,074 Dudley Feb. 14, 1950 2,500,617 Meigs Mar. 14, 1950 2,534,588 Frost Dec. 19, 1950 2,681,617 Worthen et al. June 22, 1954 2,810,341 Neugebauer et al. Oct. 22, 1957 FOREIGN PATENTS 52,292 Denmark Oct. 12, 1936 550,575 Germany May 12, 1932 OTHER REFERENCES Sutermeister: The Story of Papermaking, page 45.

Casey: Pulp and Paper, vol. 1, published 1952 by Interscience Publishers, Inc., N.Y., page 48.

Stephenson: Pulp and Paper Manufacture, vol. 1, first ed., 2nd impression, 1950. McGraw-Hill Book Co., Inc., page 41.

Sindall: An Elementary Manual of Paper Technology, pub. by Charles Griffen and Co., Ltd., London, 1910, pages 165 and 166.

Sutermeister: The Story of Papermaking, pub. by S. D. Warren Co., Boston, 1954, pages 42-44. 

1. AN ELECTRO-RESPONSIVE PLANOGRAPHIC PLATE ESPECIALLY PREPARED TO PRODUCE A FACSIMILE RECORD BY ELECTROLYTIC ACTION IN RESPONSE TO APPLIED VOLTAGE AT SELECTED AREAS OF THE PLATE, SAID PLATE CONSISTING OF A PAPER HAVING AT LEAST 50 PERCENT HARDWOOD SULFITE PULP MIXED WITH A WET STRENGTH IMPARTING INGREDIENT, SAID PAPER HAVING INCORPORATED TEHREIN DURING MANUFACTURE A WATER RESISTANT BUT HYDROPHILIC MATERIAL TO PROVIDE THE PAPER WITH A SMOOTH HYDROPHILIC WATER RESISTANT SURFACE, THE PAPER ALSO CONTAINING AN IMPREGNATION OF A CHEMICAL ELECTROLYTIC MARKING COMPOUND TO RENDER TI ELECTRICALLY RESPONSIVE TO APPLIED VOLTAGES TO PRODUCE CORRESPONDING RECORD MARKED AREAS WHICH ARE INK RECEPTIVE. 